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Discussion Starter #1
I recently purchased a BG800 and I've been reading the post for a week now. The more I read the more confused I get. Just when I think I understand, I read another post and WHAM! now which is the best way that one or this one. Basically I'm very new to HT but I'm eager to learn and start. I have an HT area of 16'x22'7" with 8' ceiling. Plan to do a ceiling mount. I'm very confused on the subject of aspect ratio, screen size, and gain for my BG800. I have control of ambient light. I plan to view DVDs and computer games(limited)on my projector. I would like to use a DIY wall mounted screen, size 52x92 16:9 with Blackout material (Haven't figured out what blackout material is yet, still reading) Will this work with the BG800? There is a very good post on how to make this screen and this is the driving factor behind my decision. Plan to buy a commercial grade screen once my funds regroup from the projector purchase.


Anyone from the Pensacola Fl area doing HTs?


Thanks for any suggestion!


Andre

Semper Fi

 

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I used a homemade screen with my BG800 until just this week. The blackout material can be purchased at stores that sell cloth by the yard (but call ahead first). If I remember right, the width is 54 inches so that is your maximum vertical measurement, and you determine the length which will be the width of your completed screen. I just attached mine to a long dowell and hung it from hooks in the ceiling.

One note of caution with the BG800-if you adjust the Schlemplug (?) corner focus-don't over do it! I shorted out my RGB board on the blue tube and had to buy a replacement from Curt Palme who sells and repairs projectors.

My projectors is floor mounted and I am now using a Dalite screen that has gain. This does make for a brighter and sharper picture than the homemade one. But I think you will be pleasantly surprised just how well the black out material works. Good Luck!

Dave
 

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Hi Andre,


Sorry to hear you confused about so many things! http://www.avsforum.com/ubb/frown.gif I guess sometimes there's just too much info here http://www.avsforum.com/ubb/smile.gif


Can you be a little more precise about what it is you are confused about? You say "aspect ratio" - do you mean the aspect ratio of the screen? What will you be using to play the DVDs with - HTPC or DVD player or...? Answers to these questions will let people give you better answers i think.


I'll try to give you some info here, all this i learned myself here on the forum. If some of this is incorrect, it's entirely my fault http://www.avsforum.com/ubb/smile.gif


Blackout material

I made my own screen from blackout material that i bought at a local fabric store (Joann's). Blackout material is a kind of material that does not let light through. Normally it's used as an extra layer people put between curtains and windows, so that light gets blocked out and doesnt seep into a room. Hence the name blackout material. This material is actually very white, and therefore very useable as screen material. The material comes in rolls that are 54" wide, so like Dave pointed out, that would enable you to make a screen that's about 96"x54". People have described the blackout material as having a gain of about 1.0.


Gain

A gain of 1.0 means that the light that the projector throws onto the screen is bounced off of the screen in all directions. That means that it doesnt really matter where you sit in relation to the screen, because you'll see a picture of equal brightness everywhere. The drawback to a gain of 1.0 (low gain) is that because the light gets scattered in all directions, the amount of light that actually reaches your eyes is "low" as well, because the light that comes out of the projector gets distributed across a large area by the screen.


That's where screens with higher gains (1.3, 1.5, 2.0 etc) come in. A higher gain screen reflects the light from the projector back into a narrower area than a lower gain screen. The higher the gain, the narrower this area is. The benefit of doing this is that now the amount of light that reaches your eyes is higher, because the light that comes out of your projector gets distributed across a smaller area. The drawback is that if you sit off to a side, less light will now reach your eyes, because most of the light is focussed inside the narrower area i described. Also, with this higher gain, you'll start to see "hot spotting", which means that the image seems to be dimmer towards the edges of the picture. The higher the gain, the stronger this effect.


A crude way to illustrate gain: instead of your screen, picture a flat mirror, and picture a light bulb in front of it in the center of the mirror. If it's just a plain clear light bulb in a socket, the light from the light bulb will shine in all directions, and because the mirror is flat, the light will be reflected into all directions equally. No matter where you sit in relation to the lightbulb, the bulb will look equally bright everywhere. This would correspond to a gain of 1.0. Now picture making the mirror slightly hollow, bending the corners of the mirror slightly forward. The light will now be focussed straight ahead a little more. If you sit straight in front of the mirror / bulb, the light will look brighter to you then when you sit off to the side. If you increase the "hollowness" of the mirror, the effect will get stronger. This is similar to increasing the gain.


So there's a balance to be found. Low gain means a evenly bright image from "all" viewing angles, but the picture is relatively dim. A higher gain means a brighter picture in the ideal viewing spot, but a dimmer image when you sit off to the sides.


Making your own screen

The way i went about making my screen is:


I went to Home Depot and bought some lumber (pine), some screws, and a few L brackets. I cut the pieces of wood so that i could make a frame out of them. I cut it so that the inside of the frame would be the size of the screen i wanted (in my case 127"x54"). I attached the L brackets to the screen to give it some more strength.


I went to Joann's and bought the blackout material in the length i needed for my screen, and i bought some black fabric (felt) that i would use to wrap around the frame to make it look nicer and make it more light absorbing. (A dark black border around your picture helps increase the perceived contrast of the picture.)


I cut the black velt to pieces i could wrap around the frame, and used a staple gun to staple it to the frame on the back side of the frame (side that would be against the wall). So the seam of the black material was on the back of the frame.


Then i used a staple gun to staple the blackout fabric to the back of the frame as well. The fabric actually stretches quite a bit, it's kinda elastic, so you can use the 54" wide material to cover the 54" wide opening in the frame and by stretching the material you'll still have plenty of material on both sides to staple it to the frame.


As for mounting - i wasnt quite sure at first how i wanted to put the screen against the wall. Especially since i first had my projector on the ground, and i would have to put the screen at the right height for that, but i was planning on ceiling mounting the projector, and then the screen perhaps would have to be at a different height. I was experimenting a lot with distance etc, so i was very reluctant to permanently mount the screen to the wall. So what i ended up doing was getting the wide industrial strength velcro from Home Depot. I put two vertical strips (the non-fuzzy part of the velcro) on the wall from veiling to floor right where the sides of the frame would go. Then i put the other velcro strips (the fuzzy ones) on the back of the frame on the vertical parts. I stapled this with LOTS of staples (i found out that using only a few staples was not good since the velcro is STRONG, and when you try to pull the screen off again, the velcro will come off if you dont use enough staples).


Now i was able to put the screen against the wall, remove it, reposition it and stick it back against the wall, all without any trouble http://www.avsforum.com/ubb/smile.gif


After that, i had my screen http://www.avsforum.com/ubb/smile.gif Pretty simple huh? I didnt worry about re-enforcing the frame much since it would be mounted against a wall and therefore wouldn't need a lot of strength. If you plan on not mounting your screen to the wall however, you may want to try some different methods of constructing your screen frame. Do a search on the forum in the screen area and search for "DIY screen", i'm sure you'll find a lot of info there.


Phew, lots of typing there. I hope some of this info is of use to you http://www.avsforum.com/ubb/smile.gif


Cheers,


Gertjan


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Discussion Starter #4
Thank for the great post. Gertjan, thank for the post on gain, I'll print and keep. I got information overload from reading so many different post and the slang is still new to me. Here's more on info on my HT plans.


1. Plan to run dvd player with BG800. Later will add HTPC, still need more info on what an HTPC does for viewing pleasure.


2. Will I need a line doubler to get good picture from my DVD player?


3. Plan to also run PC through Composite video (don't know if that the right terminology) this will be for limited gaming playing (flight Sims)


4. From my reading, I think I'll do 16:9 but what is all this talk about masking for 4:3.


5. Is ceiling mount any better than floor mount if you have the space. I've been quoted a much cheaper price for calibration on floor mount by my local Pro projector installer.



Sorry about the Newbie question but I have to ask to learn. Thank for all your support and help.


Andre

Semper Fi


[This message has been edited by Fraza (edited 10-11-2001).]
 

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Hi Andre,


Glad you liked my post http://www.avsforum.com/ubb/smile.gif Let's see if i can help you out some more...


As for 1 and 2:

A projector can display pictures with "any" resolution, as in, it's not a fixed resolution device (unlike a LCD screen that has a fixed number of pixels horizontally and vertically). The projector will try to adapt itself to the resolution you feed into it and display that on your screen.


A DVD picture is 720x480 pixels (here in the US anyway). A typical standalone DVD player will output the DVD picture in its 720x480 pixels resolution. If you use such a DVD player to feed the video signal directly into a projector, the projector will display the picture in the 720x480 resolution on your screen. Since a screen is so big, the picture will not look as good as it could look. It'll show horizontal black lines between the lines of the picture.


Now for a HTPC. I'll limit myself to a computer running Windows btw.


When you hook up a PC to a projector, the projector will project the resolution of the Windows desktop onto the screen. So if you have your display settings set for 640x480, the projector will display that on the screen, again with the black lines between the lines of the picture. But since most projectors are capable of higher resolutions, it would make more sense to set your Windows desktop to a higher resolution. The higher the resolution, the closer the lines will be to each other on the screen, and the "smoother" the picture will look. It'll look more like film than TV.


Now the cool thing that PCs can do is that when you play a DVD (or video clip from an AVI file or whatever other video), it can scale the video to fill up the entire Windows desktop. So the DVD picture that was only 720x480 would then be scaled up to whatever size you set your windows desktop at. So a DVD image can then be 1280x720 pixels for example. The computer will come up with the extra pixels that need to go between the original 720x480 pixels, and is pretty good at that. Now if you send -that- picture to the projector, the projector will display the full 1280x720 pixels on your screen. Now the picture on the screen will look much more solid / smooth and more film-like.


Also, a HTPC can do some neat tricks with the DVD video material to make it look even better. These things normally are done only by the higher-end stand alone DVD players. Things like 3:2 pulldown to make the picture look even more film-like.


You can buy external stand alone scalers / line doublers/triplers/quadruplers that do the same thing a HTPC does, just these are boxes you put between your DVD player and the projector.


So basically, if you get a projector, you should get -some- sort of device to create a smoother / higher resolution picture to feed into your projector, otherwise it would be such a waste of the projector. If you're into that kind of stuff, a HTPC is a cool toy. It just takes some technical skills. A "box" line doubler/tripler/quadrupler is much more user friendly, it's just plug-and-play.


Check out this thread, it deals with probably everything you might want to know about HTPC: http://www.avsforum.com/ubb/Forum12/HTML/010519.html


3:

Running the PC through composite? I think you may be thinking of the wrong term here. I don't know your projector, so i may be assuming the wrong things here, so if anybody knows anything more about this projector, feel free to correct me if i'm wrong. But anyway. Typically you'd not use composite video to feed into a projector. My projector (Marquee 8501LC) takes RGBHV as input. This means i have 5 BNC connectors on the projector that i connect my HTPC to. On the HTPC end i use the VGA out (the 15 pin connector) that normally goes straight to the coputer monitor. The cable "converts" the VGA connector to the 5 BNC plugs that the projector wants. Whatever you do on the PC, you'll see on the screen through the projector. So any PC game you play will be projected on the big screen http://www.avsforum.com/ubb/smile.gif A projector + screen is really nothing more than a fancy computer monitor. Keep that in mind.


In case you're talking about a console game computer, like a DreamCast or PlayStation, then i would recommend feeding the signal through a HTPC. THat's what i do anyway. In my HTPC i have a video input card that take svideo and composite video as input. Using "special" software (dScaler), i can take any video source (in this case my DreamCast) and let dScaler blow up the image to fill up my Windows desktop again, and then that is shown on my screen.


Pretty much the same logic applies here as with the DVD picture. Yes, you could feed the picture straight into the projector, but you'd be missing out on a lot. If you use a device in between, either a line doubler/tripler/quadrupler or a HTPC, the picture can look much better.


Again, i dont know your projector, i do not know what kind of inputs are on it.



4:

When you have a 16:9 screen, 16:9 material (movies) will look great, they'll take up the entire screen. If you project 4:3 material however (standard video sources like a console game computer or a VCR or regular broadcast material), the 4:3 image will not fill up the entire screen obviously. If you have a fully light controlled room this is not such a big deal. The thing is though, the part of the screen that's not being used may look a little grey instead of black, because the screen -is- white, and either ambient light and / or light that splashes back onto the screen off of the wall / ceiling / floor will get onto the screen there, and make the unused area light up just a little bit. Some people find that annoying. They use "masking" to mask off the unused area of the screen, and they use black material for this. Kinda like in the theater - if you pay attention at the beginning of the movie, a lot of times you'll see that the sides of the screen slide out or in, depending on the movie. This is done to "frame" the picture in black so that the contrast level of the picture seems better. It's an optical thing. It's not necessary at all to enjoy your home theater. It's just an extra thing you can do if you so desire.


5:

Ceiling mount vs floor mount really is a personal preference. Ceiling mount seems to be the best, since the projector will be out of your way and thus leaves more floorspace for you to use, and also that way nobody can accidentally move the projector and thereby throw of the focus and alignment etc etc. Because once you've set up your projector fully, you dont want to move it at all, or the picture will suffer from it and you'll need to readjust all the focussing etc on your projector to compensate. It all depends on if you -can- do it in your room, and on how you plan to use the room. If the room will see "high volumes of traffic", as in people / kids / pets will be walking through constantly, a floor mount is probably not a very good idea. It all depends on your personal preference though. It's a matter practicality, either mounting will not make a difference in picture quality as far as i can tell.



Hope that answers some of your questions again.


And don't worry about asking newbie questiongs. I was in the newbie position myself not too long ago, so i know how you feel http://www.avsforum.com/ubb/smile.gif Now i can at least pay back to the forum some by sharing my experience with newbies like you http://www.avsforum.com/ubb/smile.gif One word of advice though - do some searches in the different forums before you ask too many questions. Many of these questions have been asked many times before by many newbies before you, and have been answered by knowledgable people in the past. All these questions and answers are all still available on the forums, either in the active forums or in the archives. You can search through them, and often you'll find a lot of the info you're looking for that way. I know it's kind of intimidating to wade through all the information that may pop up, but it's worth it. And the regular forum members will appreciate it much more if you try to do your homework yourself first http://www.avsforum.com/ubb/smile.gif So try to make yourself familiar with the search function of this forum, using some simple keywords like "HTPC" or "aspect ratio" or "ceiling mount vs floor mount". You should be able to dig up a lot more info than i can give you here in a few posts http://www.avsforum.com/ubb/smile.gif


Good luck


Gertjan


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He who asks is a fool for five minutes, but he who does not ask remains a fool forever.
 

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Gertjan

I'm in a same boat with Fraza, and just want to say thank for your helpful post. It give me a basic idea to start.
 

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You're welcome, i'm glad it's useful to you http://www.avsforum.com/ubb/smile.gif


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Andre, I live in Pensacola, give me an E-mail and one day soon I'll come over and give you a hand.

I've had a couple hours experience with an 808s, it was very easy, and quick to get a decent picture.


Just noticed the e-mail function seems to be gone, it'[email protected]
 

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Gertjan,


More thanks from a newbie lurker. Those were very informative posts. Your time is appreciated.


-Nathan
 

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Obviously Gertjan was smart enough (or young enough) to take typing in school.


I'm so jealous!


Curt
 

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Curt - it's just the growing up behind a computer that does that to you... if i put down my hands they automatically are in the shape that matches the keyboard. j/k of course :)
 
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